1. Preheat oven to 180°C. Spray a 23cm x 3cm deep, round, loose bottom, fluted flan tin with olive oil.
2. Cut half of one of the zucchinis into thin rounds. Grate remaining zucchini and set aside.
3. Heat oil in a non-stick frying pan over a medium heat. Cook onion for 5 minutes, stirring occasionally, until softened. Add bacon and cook for 5 minutes longer. Add grated zucchini and cook for another 2 minutes. Add pepper and half the thyme and stir to combine. Set aside.
4. Cut pastry sheets in half to form 16 squares. Use pastry sheets to line the base and sides of the flan tin, overlapping them to fit and allowing edges to overhang the rim. Spray each sheet with olive oil before placing down the next sheet. Scrunch up overhanging pastry to form a rim. Place the flan tin on a baking tray.
5. Add cheese to zucchini mixture and stir to combine. Spread over base of pastry lined flan tin. Top with reserved zucchini rounds.
6. Place the cornflour in a bowl. Gradually blend with ¼ cup of the milk. Add the remaining milk and eggs and whisk to combine. Carefully pour over filling. Sprinkle with the remaining thyme leaves.
7. Bake 45-50 minutes or until set.